Production of ferrosilicon aluminum



W. B. D. PENNIMAN AND R. 8. WHITE.

PRODUCTION OF FERROSILICON ALUMINUM.

APPLICATION FILED JUNE 9, 1919.

1,369,298. Patented Feb. 22,1921.

WILLIAM B. D. PENNIMAN AND ROY S. WHITE, OF BALTIMORE, MARYLAND.

PRODUCTION OF FERROSILICON ALUMINUM.

Specification of Letters Patent.

Patented Feb. 22, 1921.

Application filed. June 9, 1919. Serial No. 302,863.

This invention relates to the direct roduction on a commercial scale of a comblnation of aluminum, iron and silicon, known as ferro-silicon aluminum.

In the manufacture of ferro-silicon, which is used as a scavenging or purging agent in the production of cast iron and steel, a small amount of aluminum sometimes appears as an impurity. This is distinguished from the subject of the present disclosure, first, by the fact that this small amount of aluminum occurs as a result of what must be considered an impurity in the materialsused in the manufacture of ferrosilicon, because this aluminum content in the materials is a disadvantage in the manufacture of ferro-silicon as now practised, and, second, in the product, aluminum is not present in amounts suflicient to be of prac- 4 tical advantage to the maker of ferro-silicon or the user of it, and it is not customary to make any financial allowance. for its presence or to consider it as a factor in the use of the ferro-silicon or its application to the arts.

The presence of these impurities containing aluminum in the materials used in the manufacture of ferro-silicon is to be avoided under ordinary conditions because they give rise to a troublesome sla which has such a. high melting point that 1t is diflicult to remove from the furnace and separate from the ferro-silicon. These im urities as they have occurred also give 0 an increased amount of dust, the proportion of aluminum oxid found in such dust being far in excess of the proportion of aluminum oxid present in the ores and other constituents introduced into the furnace, so that the aluminum content in the materials is mostly lost and only small amounts in proportion appear in the ferro-silicon.

In our experience operating with these impure materials the amount of aluminum found in ferro-sil-icon is generally much less than 1% and seldom, if ever, exceeds 2%.

It is Well known that an alloy or combination of aluminum, iron and silicon is on the market and is known as ferro-silicon aluminum. This combination is effected,

however, by making in separate and distinctoperations, ferro-silicon and metallic alummum, wh1ch.are afterward melted and compounded together to form the desired product.

Our invention comprises a new method of making an alloy of aluminum, iron and silicon which has evident "advantages so far as cost and convenience of manufacture on a large scale are concerned.

The product of the process which is the sub ect of this invention contains on an average of from 15 to 20% aluminum and is intended to include any per cent. from 3. or 4 to 50%.

At the present time large quantities of ferro-silicon are used as a scavenger or purging agent in the manufacture of iron and steel. It is also customary to use metallic alumlnum for the same general purposes; sometimes both of them are used in the same batch of metal, ferro-silicon being used first and the aluminum afterward, as'

the latter is generally considered a more actlve agent in removing impurities and it is also believed to have an effect upon certain substances that are not affected by the ferro-silicon.

Metallic aluminum is however used at great disadvantage, first, on account of its expense and, second, on account of the waste.

vThe latter arises from the fact that the aluminum as the metal is protected in a large measure from oxidation by the air and in this combination with the other con: stituents of the alloy, it can be introduced much more effectively into the body of molten steel or iron.

It is wellknown that the production of aluminum 1S necessarily expensive on 9.0-

count of the purity of the materials required and the comparative complexity of the apparatus used. When the ferro-silicon-aluminum is made direct from ferrosilicon and aluminum, there is the high cost inherent to the production of aluminum and also the losses of aluminum that occur when the metal is combined with ferro-si licon. These losses of aluminum are not perhaps as great as in the ordinary practice of steel or iron making but they are so large that the price of ferro-silicon-aluminum is high and ranges far above the cost of the ferro-silicon and aluminum purchased separately. On the other hand, ferro-silicon-aluminum can be made according to this invention direct from cheap iron, silicon and aluminum compounds which occur abundantly in nature.

In the early development of the invention the product, i. e., ferro-silicon-aluminum was produced by treating brick bats and coke in an electric furnace, such as is ordinarily used for making ferro-silicon, the proportions by weight being seven of brick to nine of coke. The brick-bats and the ash of the coke are both intimate mixtures orchemical combinations of aluminum oxids, silicon and iron oxids, and similar except as to the presence of small and unimportant amounts of other substances. By proper management'of the furnace the desired material was obtained as indicated below.

To reducestill further the loss by way of the stack and the difliculties of slag formation we may preferably, though not necessaril as a partial source of aluminum, use some compound of aluminum and silica that contains in addition other material or materials that act. as a flux. By preference we um avoided.

have been using. commercial feldspar which is in the main potassium aluminum silicate. In practice an lmpure feldspar may be used or the fiuxing material may be some other compound. This fiuxing material may be introduced as a separate substance. At the present time ordinary feldspar is the best material as it is cheap and plentiful,'particularly as we do not require the high quality of feldspar that is necessary for other industrial uses and can in' consequence avail ourselves of what would otherwise be a waste product at the mines where feldspar is produced.

In the practice of the method of the invention, both the slagging andeonsequent loss of aluminum and dust losses by volatilization of aluminum oxids are in a large meas- The materials are mixed in proportionsdetermined by the roduct desired and fed gradually into the urnace. It is important that the arc should be kept covered as far as possible and the electrodes well under the charge. The spacing of the electrodes is make and the market proportionate amount of aluminum and less iron and silica can be added to the mixture or a clay or clay product, containing less iron or silicon may be used. It is also true that at times we find it advisable with the materials indicated above to add either iron oxid or metallic iron or silica in the form of-slhca rock. These variatlons in materials depend upon the kind of alloy we desire to ores available. By using selected mate ials the amount of aluminum can be carried as high as 30 to 40% or even 50%. As'an example of the flexibility with which the process can be applied with a saving of cost of raw materials and in this instance with a better yield, we have used the following materials to produce (practically the same alloy as that indicate above:

. 150 pounds feldspar.

150 pounds coke.

25 pounds iron ore (90% iron oxid).

In this particular case the product contained 44.15% silica, 40.10% iron and 15.64% aluminum. It should be stated that the figures given above only show proportions as our operations h ve beenon a large scale.

rice of the different with iron .compound'or iron, in the presence. v

of a reducing agent substantially as described.-

In the accompanying drawing, we have illustrated an electric furnace equipped for the production of ferro-silicon aluminum, in accordance with my invention, showing the preferred arrangement of the charge 1n relation to the electrodes. The details are not, however, essential to the invention but ma be widely varied.

'I he figure is a transverse section on a vertical plane and so placed as to disclose the electrodes in elevation.

, in an electric furnace The furnace structure, 1, as shown, is

built of fire bricks, 2, or any convenient ma terlal suitable to such structures, the furnace walls being formed ,toeinclose a cavity or' chamber, 3, for the cha.rge,"- the bottom of the cavity being, in theform of theinvention shown, coated or lined with a suitable fire.- roof cement or similar plastic, 4.

T e buses, 5, 6, 7, connections48, 9, 10,

- ficient definiteness to enable those skilled in the correlated metallurgical arts to practise the invention; however, these specific terms and details are used in a descriptive rather than a limiting sense, the scope of the invention being defined in the claims.

7 What we claim and desire to secure by Letters Patent is:

1. A method of making ferro-silicon aluminum alloy which consists in treating compounds of aluminum and silicon and iron and a reducing agent in an electric furnace, substantially as described.

2. A method of making a ferro-silicon aluminum alloy which consists in treating compounds of aluminum and silicon and iron and a reducing agent with a flux in an electric furnace, substantially as described.

3. A method of making a ferro-sili'con aluminum alloy which consists in treating compounds of silica and aluminum and iron in the presence of a reducing agentin an electric furnace, the materials being thoroughly mixed, substantially as described.

4:. A method of making a ferro-silicon aluminum alloy which consists .in treating compounds of silicon and aluminum with iron in the presence of a reducing agent in an electric furnace, the materials being thoroughly mixed and fed gradually, substantially as described.

5. A method of making a ferro-silicon aluminum alloy containing three to twenty per cent. of aluminum which consists in treating compounds of silicon and aluminum.

with iron in the presence of a reducing agent in an electric furnace, the materials being thoroughly mixed and fed gradually, and the electrodes being kept covered with the materials, substantially as described.

6. A method of making a ferro-silicon aluminum alloy containing 3 to 50% aluminum which consists in treating compounds of aluminum and silicon with iron in the presence of a reducing agent in an electric furnace, bauxite being added to increase the aluminum content, substantially as described.

7. A method of making ferro-silicon alu- 'minum alloy containing over 3% of aluminum which consists in treating feldspar in an electric furnace in the presence of a reducing agent, the furnace mix also including iron, substantially as descrlbed.

Signed, by us at Baltimore, Maryland, this 2nd day of June, 1919.

WILLIAM B. D. PENN IMAN. ROY b. WHITE. Witnesses:

ALFRED C. HATCH, EDWIN F. Simmons. 

